The present invention relates to a phosphorescent material which is capable of emitting light in the darkness when it is irradiated with light, and in particular, to a liquefied color phosphorescent material which is capable of always maintaining a three-dimensionally uniform dispersion state of pigment particles and phosphorescent particles in the phosphorescent material, thereby making it possible to control the color tone of emitting light (the adjustment of color tone and the resolution of color) and also to control the color tone of colorant which is visual under a lighted condition such as daylight.
It has been conventionally known that when the phosphorescent paint is excited by the irradiation of sun light, ultraviolet rays, electric light, etc., the energy thereof is accumulated in the phosphorescent paint and the energy thus accumulated is subsequently gradually converted into light after the suspension of the irradiation of light, thereby emitting light. Since this phosphorescent paint is capable of emitting light in the darkness, this phosphorescent paint has been practically employed in the fabrication of the face of watch, various marks, etc. In recent years, this phosphorescent paint has been utilized even in so-called fashion goods such as shoes, and there is an increasing demand for such phosphorescent paint.
Under these circumstances, the phosphorescent paint is now demanded to have various characteristics, i.e. it can be easily coated irrespective of the kinds of object to be coated, the fluorescence to be emitted is uniform, and the coated surface to be obtained is smooth. Among various kinds of the phosphorescent paint, the paint whose end-use as well as utilization are expected to be expanded in future, if realized, would be the one which is capable of emitting a light of desired color (for example, a phosphorescent paint which is capable of emitting a red color, or a blue color).
Further, if it is possible to realize a phosphorescent material wherein the color tone which is visual under a lighted condition such as daylight (hereinafter referred to as under visual condition) differs from the color of emitting light in the darkness, or a phosphorescent material which is capable of delicately controlling the color of emitting light to a desired color, the end-use of the phosphorescent material can be further expanded, and hence the industrial utility thereof can be further promoted.
The luminescent color to be emitted in the darkness from the phosphorescent paint according to the prior art is limited to a light green color irrespective of the kinds of color under visual condition. Under the circumstances, various renovations of phosphorescent paint have been attempted with a view to develop a phosphorescent paint which is capable of emitting different kinds of luminescent color.
In this respect, there is suggested an idea as seen for example in Japanese Patent Registration No. 2866123 (Unexamined Pub. No. H03-166269) and Japanese Patent Unexamined Publication H11-158420, wherein the addition of fluorescent paints or organic pigments to a phosphorescent paint is suggested.
However, even if it is possible prevent the generation of color skipping of color tone under visual condition by the addition of fluorescent paints or organic pigments to a phosphorescent paint, the luminescent color to be emitted therefrom is still light green. Even if it may be possible to alter the luminescent color more or less, the range of alteration of the luminescent color is extremely limited (see Japanese Patent Unexamined Publication H11-158420, paragraph [0014]). Namely, it is far from possible to obtain a desired luminescent color.
On the other hand, phosphorescent color paints for obtaining various kinds of luminescent color is also suggested. These phosphorescent color paints according to the prior art are formed of a mixture comprising a color pigment, a phosphorescent agent and an anti-sediment agent.
However, as shown in FIG. 6, these conventional phosphorescent paints are defective in that when these phosphorescent paints are applied for example by means of brushing or wiping, the phosphorescent agent 2 thereof is allowed to sediment with time and to settle on the underlying substrate 3 due to a relatively large specific gravity of the phosphorescent agent 2, resulting in that the layer of the phosphorescent agent 2 thus settled is ultimately covered by the color pigment 1. Namely, the employment of only the conventional anti-sediment agent is substantially ineffective in preventing the sedimentation of the phosphorescent agent 2.
As a result, light or ultraviolet ray is shut out by the color pigment 1, thereby preventing the light or ultraviolet ray from being sufficiently absorbed by the phosphorescent agent 2. Accordingly, these phosphorescent paints are accompanied with drawbacks in that it is difficult to secure a constant luminescence, that the luminous intensity is poor or becomes substantially zero if the color pigment 1 is coated thickly, and that the surface of coating thereof is poor in smoothness.
Further, since it is impossible to secure constant luminescence and luminous intensity, if these phosphorescent paints are desired to be coated on a colored or patterned surface of substrate, a white paint is required to be primed in advance on this colored or patterned surface of substrate prior to the coating of these phosphorescent paints. As a result, the applicability of these phosphorescent paints and sheets is caused to be limited.
Under the circumstances, various kinds of invention are suggested as seen from Japanese Patent Unexamined Publication 2000-109730; and Japanese Patent Unexamined Publication 2000-107681, wherein phosphorescent particles are mixed with a transparent clear paint so to mainly improve the luminous intensity on the occasion of emission and also improve the luminescence time.
However, it is impossible, even with these inventions, to realize a luminescence of desired color. The main feature of these inventions resides in that through the emission of the transparent clear paint layer (actually, translucent), the color of the underlying layer disposed below the clear paint layer is utilized as a luminescent color. However, since the layer giving the emission of light is confined to the translucent paint layer, the color of the underlying layer will be simply recognized as a monotone, so that even if it is possible to obtain a constant luminous intensity, it is impossible to make it visualize as the color aimed at. Namely, it is almost impossible even with the aforementioned inventions to obtain a luminescent color as desired.
Additionally, it is required, according to these inventions, to spray a phosphorescent paint to a uniform thickness by making use of a special machine (see paragraph [0009] of Japanese Patent Unexamined Publication 2000-109730 and paragraph [0009] of Japanese Patent Unexamined Publication 2000-107681). Namely, unless this special machine is employed, it is impossible to perform the painting. Moreover, since a thinner is employed in these inventions, it would be difficult to apply the phosphorescent paints of these inventions to plastic chips or to textile products. Namely, the phosphorescent paints of these inventions cannot be freely coated, and the objects to which this coating would be applicable may be restricted.
On the other hand, the particle size of phosphorescent pigments employed in the conventional phosphorescent materials is not uniform. As a result, due to the effects of friction by the non-uniform phosphorescent particles or of hardness of the non-uniform phosphorescent particles, there have been much possibilities to damage or destroy the working equipments, machine or machine components in each of working processes using the non-uniform phosphorescent material. Moreover, the employment of the non-uniform phosphorescent particles leads to various troubles in the printing process thereof that unless a screen printing plate of large mesh is employed, the clogging or damaging of the screen printing plate would be caused to occur, and that due to the friction of phosphorescent pigment particles on the occasion of printing thereof, heat is caused to generate to thereby dry the ink. As a result, automation apparatuses, machines or machine members useful for the conventional phosphorescent material are limited because of the aforementioned reasons.
In the case of phosphorescent materials where the usefulness thereof is based on the diffusion and dispersion thereof in the surface layer of coating, the effects of phosphorescent emission as well as the effects of color under visual condition that may be brought about by the effects of dispersion of phosphorescent materials cannot be fully attained unless the phosphorescent materials are coated to a predetermined thickness or more. Therefore, it has been impossible to print the phosphorescent materials into a fine dot pattern.
It has been found that the aforementioned problems can be overcome by taking measures that the phosphorescent material is liquefied, that the particle size of coloring pigments and phosphorescent pigments to be mingled in the liquefied phosphorescent material is confined to a predetermined value, and that these coloring pigments and phosphorescent pigments are enabled to be always maintained in a substantially uniform dispersion state in the three-dimensional direction irrespective of when the phosphorescent material is in a liquefied state or in a solid state.
The present invention has been accomplished based on the aforementioned viewpoints, and therefore, the present invention provides a liquefied color phosphorescent material consisting of a mixture which mainly comprises; a stock solution consisting of a thermoplastic resin and an organic solvent; a colorant containing a coloring pigment; a color-emitting phosphorescent fine pigment particle having an average particle diameter of 7 xcexcm or less; and an additive for stably dispersing pigments containing a cellulose-based synthetic resin, silica-based powder, cyclohexanone, isophorone and mineral spirit.
The color phosphorescent material and the method thereof according to the present invention are featured in that they utilize the effects that the color pigment and the phosphorescent pigment are enabled to be always maintained in a substantially uniform dispersion state in all of the three-dimensional direction irrespective of when the phosphorescent material is in a liquefied state or in a solid state, and hence the present invention quite differs from the conventional idea and technique.
Namely, according to the color phosphorescent material and the manufacturing method of the present invention, the coloring pigment and the phosphorescent pigment are enabled to be always maintained in a substantially uniform diffused and dispersion state in all of the three-dimensional direction, without causing the coloring pigment and the phosphorescent pigment to be settled or to become non-uniform, thereby making it possible to realize a desired phosphorescent color and to delicately control the tone of phosphorescent color. Additionally, the color phosphorescent material and the method thereof according to the present invention are designed such that even if the phosphorescent is coated directly over a colored substrate or a patterned substrate without applying an undercoating using a color paint, it is possible to enhance the phosphorescent color-emitting efficiency and to keep a constant luminous intensity for a longer period of time.